Clover is a Code Coverage tool for Java. It finds sections of your code that are not being tested. This helps you improve your unit tests and find more bugs, before your customers do.

Clover integrates easily into Ant-based builds and provides accurate and detailed measurement of method, statement and branch coverage. Because it requires no specialized runtime, it is well suited to testing of J2EE applications.

Clover reports in XML, HTML, PDF, or plain text. A Swing Viewer allows interactive browsing of Coverage results. Historical reporting provides charting of code coverage and other project metrics over time. A suite of Ant tasks provide control over all aspects of the coverage gathering and reporting process.

Clover 1.2.1 includes bugfixes and minor improvements, along with new fully integrated plugins for IntelliJ IDEA, NetBeans, and Eclipse. These plugins allow you to measure and inspect code coverage without leaving the IDE. The Clover Ant task now allows better historical reporting, custom links from HTML reports and more.

Having used Clover extensively in both the Spring Framework (open source) and commercial projects, I'm very happy with it. It's easy to use and the Javadoc-style HTML reports are very readable.

It's important to remember that code coverage is only one metric and that unit tests are about testing functionality, not just achieving high code coverage, but a good coverage tool like Clover can reveal a lot about a code base and help make significant improvements.

From the announcement:
Clover 1.2.1 includes bugfixes and minor improvements, along with new fully integrated plugins for IntelliJ IDEA, NetBeans, and Eclipse. These plugins allow you to measure and inspect code coverage without leaving the IDE.

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